We developed three analog logic SPICE (Simulation Program with Integrated Circuit Emphasis, developed at the University of California, Berkeley, CA) subcircuits, a voltage comparator and a nonlinear waveform generator to compliment the previously derived functions (Goldstein and Rypins, Comput. Methods Programs Biomed. 29 (1989) 161-172) that simplify modeling of physiologic systems. The logic elements are the 'AND', 'OR' and 'NOT' Boolean functions. In addition, we derived a voltage comparator for use in our composite waveform generator. All the circuits are analog so they can be incorporated into existing analog circuits while performing digital functions. © 1990.
Goldstein, L. J., & Rypins, E. B. (1990). Nonlinear waveform generation. Computer Methods and Programs in Biomedicine, 31(3–4), 185–193. https://doi.org/10.1016/0169-2607(90)90002-Q